1. Technical Field
This invention relates to drilling rig fingerboards, and more particularly to a fingerboard latch assembly for providing real time latch position feedback via a process control network.
2. Background Information
Oil and gas well drilling systems include numerous types of piping, referred to generally as “tubulars”. Tubulars include drill pipes, casings, and other threadably connectable oil and gas well structures. Long “strings” of joined tubulars, or drill strings, are typically used to drill a wellbore and to prevent collapse of the wellbore after drilling. The drill strings are typically stored in a structure commonly referred to as a fingerboard. Fingerboards typically include an elongated support structure(s) or “fingerboard row(s)” each capable of receiving a plurality of drill strings. Each drill string is typically individually secured to one of the finger rows by a corresponding latch, which is movable between a locked and an unlocked position. On offshore drilling rigs, these tubulars are typically stacked upright in the fingerboards, while the latches hold the tubular in place until needed.
In some fingerboards, the latches are manually moved between the locked and unlocked positions by an oil or gas well worker who walks across the fingerboards to manually move the latches to the desired locked or unlocked position. Due to the extreme height of the fingerboards, (in some instances 90 feet tall or more) the manual operation of the latches by the worker is undesirably dangerous. This practice may be particularly dangerous when the worker moves the latches between the locked and unlocked position by kicking the latches into or out of the locked position as the worker walks across the fingerboards, which is not an uncommon practice.
In an effort to make fingerboards less dangerous some manufacturers include automated latches that are pneumatically actuated. Although these latches may decrease the danger to the worker relative to the aforementioned manual approaches, they are not without drawbacks. For example, when the drilling rig operator needs to collect and use one tubular he will press a button on a control panel that will raise its latch to its unlocked position to release the tubular. However, conventional pneumatic latch controls typically do not provide feedback to the operator of the actual latch position. In some cases the latch will not raise fully and at its height on the derrick, it is generally difficult to confirm the actual position of the latch. In such a situation, a worker generally needs to climb up the derrick and walk out onto the fingerboard to determine the position of the latch. As mentioned above, the height of the fingerboard tends to make this a dangerous procedure. Moreover, in some cases the drilling rig operator will press the button again, without first determining the latch position, sending another signal in an effort to open it. This may cause the second latch behind the first to open, releasing its pipe string which may then collide with the unreleased drill pipe. This collision may damage the fingerboard making it inoperable. Since oil rigs are generally 8-10 miles off shore, service/repair of the fingerboard may be difficult and/or time consuming. Also, as a result of the collision, the pipes may be released to crash onto the rig platform below possibly harming people and causing damage.
It is also noted that by virtue of their function, any equipment used in connection with the fingerboards is prone to damage due to the relatively harsh conditions associated with the mud and salt water, such as may be carried by the tubulars as they are withdrawn from a well and placed back into the fingerboards for storage and re-use.
Thus, a need exists for a fingerboard latch actuation system that addresses drawbacks associated with the prior art.